The Subaru SVX World Network   SVX Network Forums
Live Chat!
SVX or Subaru Links
Old Lockers
Photo Post
How-To Documents
Message Archive
SVX Shop Search
IRC users:

Go Back   The Subaru SVX World Network > SVX Main Forums > MOD Mania > ECU Tune Projects

Reply
 
Thread Tools Rate Thread Display Modes
  #16  
Old 05-07-2007, 07:49 PM
kcpaz kcpaz is offline
Registered User
 
Join Date: Apr 2007
Location: Gilbert, AZ
Posts: 117
so the 2v7 can automatically adjust for forced induction??? there is no need to adjust the airflow, timing, and fuel maps when going from n/a to turbo? How does this work? I'm new to the SVX scene so pardon my ignorance, but this sounds too good to be true. No need for data-logging and adjusting sliders to eliminate knock? coming from a DSM background, this sounds like a miracle. How does this work?
Reply With Quote
  #17  
Old 05-07-2007, 08:53 PM
longassname's Avatar
longassname longassname is offline
Just some dude.
 
Join Date: Sep 2002
Location: Miami, FL
Posts: 3,986
Significant Technical Input
Optimum Air to fuel ratio and ignition timing vary according to two things, RPM and Load. Engine load can either be acurately calculated by measuring the amount of air ingested per revolution or estimated from manifold absolute pressure (reading from a MAP sensor). In systems which use a MAP sensor the shape of the table which translates the MAP sensor voltage into a load reading is particular to the mechanics of the engine; if you change cams, or turbos, or anything at all substantial the old translation table becomes inacurate. The SVX engine management system calculates load based on readings from a Mass Air Flow sensor. In Mass air flow systems the translation table which translates the voltage from the mass air flow meter into a load reading is dependent soley on the meter. Changing engine hardware does not make the load readings inaccurate unless you start ingesting more air than the mass air flow meter is able to acurately measure.

The stage 2 software has the translation table and other adjustments which match a z32 mass air flow meter. The z32 mass air flow meter is able to measure 500 hp worth of air so as long as you are making less than 500 hp or at least not a whole lot more the stage 2 engine management system is able to acurately calculate load and then adjust the afr and ignition timing to optimum for that engine load.

In the stage 2 software the tables which specify the target afr and ignition timing for each given combination of rpm and engine load include values for higher than factory load ranges based upon our experience with supercharged SVX's. Again, the optimum afr and ignition timing for any given rpm & load value do not vary according to how you get there. It doesn't matter if you use a turbo, or a supercharger, or whatever--the optimum afr and igntion timing for a given load and rpm is what it is. Different turbos etc don't change what the optimum value is for a cell in a table; they change what cells in the table you tend to operate in.

Given that you have large enough fuel injectors to deliver enough fuel, a mass air flow meter that can measure the air flow, and the correct values specified for afr and ignition timing for the entire load range a mass air flow based engine management system remains acurate and handles engine modifications well. The stage 2v7 system can handle around 500hp.



Quote:
Originally Posted by kcpaz
so the 2v7 can automatically adjust for forced induction??? there is no need to adjust the airflow, timing, and fuel maps when going from n/a to turbo? How does this work? I'm new to the SVX scene so pardon my ignorance, but this sounds too good to be true. No need for data-logging and adjusting sliders to eliminate knock? coming from a DSM background, this sounds like a miracle. How does this work?
Reply With Quote
  #18  
Old 05-07-2007, 09:02 PM
kcpaz kcpaz is offline
Registered User
 
Join Date: Apr 2007
Location: Gilbert, AZ
Posts: 117
so what AFR does the stage 2 shoot for? 11.1, 10.5? I mean there are different goals for n/a and forced induction right?

So the ECU will come up with it's own timing and fuel maps based on how much air the MAF is telling it it is recieving? What about air temp, and knock?
Reply With Quote
  #19  
Old 05-07-2007, 09:57 PM
longassname's Avatar
longassname longassname is offline
Just some dude.
 
Join Date: Sep 2002
Location: Miami, FL
Posts: 3,986
Significant Technical Input
No you aren't getting it.

What afr does it shoot for at what engine load?

At light loads the cells are likely to read something like 14.7. At moderate loads that might occur at full throttle na or part throttle under forced induction the cells are likely to read something like 12.7. At heavier loads under heavier boost the cells will read a lower afr like 11.7.

The target afr for a given engine load doesn't change depending on how you get there. You are just talking about different areas of engine operation--reading different cells.

Quote:
Originally Posted by kcpaz
so what AFR does the stage 2 shoot for? 11.1, 10.5? I mean there are different goals for n/a and forced induction right?

So the ECU will come up with it's own timing and fuel maps based on how much air the MAF is telling it it is recieving? What about air temp, and knock?
Reply With Quote
  #20  
Old 05-07-2007, 10:18 PM
longassname's Avatar
longassname longassname is offline
Just some dude.
 
Join Date: Sep 2002
Location: Miami, FL
Posts: 3,986
Significant Technical Input
I think I may have just figured out what is making you missunderstand. I bet you are thinking the fuel table specifies how much fuel to inject. It doesn't on an SVX. The ECU is able to calculate exactly how much fuel to inject to reach an afr from the mass air readings. The fuel table specifies what afr to run under the operating conditions which match a cell.

The cells in the region of the table which an na car operates is in the left side of the table. The region of the table of the table a forced induction car operates under when under boost is towards the right side of the table. Get it? Load is an axis of the fuel and timing tables. When you talk about having a lower target afr for a turbo car you aren't talking about changing the value of a cell; you are talking about reading the value out of a cell further to the right in the table.

Likewise with timing. When you talk about running less ignition timing under boost you aren't talking about changing the value of a cell; you are talking about reading the value out of a cell further to right in the table.


So long as the engine management system is able to measure the mass of air being ingested, deliver the required quantity of fuel, has tables that cover the entire load range, and has the correct values in those tables it doesn't matter what hardware you use to get the air in.
Reply With Quote
  #21  
Old 05-07-2007, 10:19 PM
kcpaz kcpaz is offline
Registered User
 
Join Date: Apr 2007
Location: Gilbert, AZ
Posts: 117
I understand that ARF will change depending on engine load (open loop/closed loop). What I'm trying to figure out is how a system that works great for n/a operation could also work great for forced induction without making any changes to anything involving the engine management. It's obvious that you are much more knowlegable than me about this. I'm just trying to figure it all out. It just sounds too good to be true


For example...

With DSM engine management (which also uses a MAF based system) we use piggyback engine management systems to compensate for larger injectors and MAF sensors that allow for a larger range of measurement. Basically we can tune our cars for maximum power with our given set-up. If we add a larger turbo and better intercooler that gives us a cooler air charge, we can change out tune and take advantage of some more power. However, these systems are all user adjustable and we make adjustments based on info recieved through data-logging. I use this system... http://www.dsmlink.com/ to tune my Galant VR4. I can make adjustments to compensate for any injectors, timing, airflow, and a bunch of other things via a laptop computer. I understand that your stage 2 system already has compensations built in for the Z32 MAF and 370 injectors. In our cars we shoot for an AFR of around 10.5 to no leaner than 12.0 on pump gas. If we experience knock, we car try to fix it by making adjustments to timing or fuel. We try to make as much power as we can given our individual circumstances and set-ups.

It just seems like injectors that work well in N/A would come up short when applied to a boosted system. Or do the 370's fall into a sweet spot where they can function great in both situations?


Again, sorry for my ignorance.
Reply With Quote
  #22  
Old 05-07-2007, 10:31 PM
longassname's Avatar
longassname longassname is offline
Just some dude.
 
Join Date: Sep 2002
Location: Miami, FL
Posts: 3,986
Significant Technical Input
Ya, you are describing work arounds. They don't have the ability to correctly reprogram the ecu so everytime you change something you have to fiddle with your engine management dongles again. You can't compare piggy back crap with the most powerful engine management system, correctly programmed.

The JECS engine management systems is extremely powerfull. Correctly programmed we can use huge injectors with no effect to idle or light cruise operation at all. The stage 3 software works fine na too (740cc injectors). That whole you can't get big injectors to idle thing is a bunch of cr*p that only applies to people who don't have the ability to write the correct software to control them. A JECS engine management system takes latency into account when calculating pulse width--it even goes a step further and takes the effect of varying battery voltage on latency into account when calculting pulse width. It doesn't matter what size injectors you use; if you put the right values into the software to match the injectors it will calculate the correct pulse width.




Quote:
Originally Posted by kcpaz
I understand that ARF will change depending on engine load (open loop/closed loop). What I'm trying to figure out is how a system that works great for n/a operation could also work great for forced induction without making any changes to anything involving the engine management. It's obvious that you are much more knowlegable than me about this. I'm just trying to figure it all out. It just sounds too good to be true


For example...

With DSM engine management (which also uses a MAF based system) we use piggyback engine management systems to compensate for larger injectors and MAF sensors that allow for a larger range of measurement. Basically we can tune our cars for maximum power with our given set-up. If we add a larger turbo and better intercooler that gives us a cooler air charge, we can change out tune and take advantage of some more power. However, these systems are all user adjustable and we make adjustments based on info recieved through data-logging. I use this system... http://www.dsmlink.com/ to tune my Galant VR4. I can make adjustments to compensate for any injectors, timing, airflow, and a bunch of other things via a laptop computer. I understand that your stage 2 system already has compensations built in for the Z32 MAF and 370 injectors. In our cars we shoot for an AFR of around 10.5 to no leaner than 12.0 on pump gas. If we experience knock, we car try to fix it by making adjustments to timing or fuel. We try to make as much power as we can given our individual circumstances and set-ups.

It just seems like injectors that work well in N/A would come up short when applied to a boosted system. Or do the 370's fall into a sweet spot where they can function great in both situations?


Again, sorry for my ignorance.
Reply With Quote
  #23  
Old 05-07-2007, 10:32 PM
kcpaz kcpaz is offline
Registered User
 
Join Date: Apr 2007
Location: Gilbert, AZ
Posts: 117
I think I get what you are saying now. What the stage 2 does is it expands the operation range of the stock ECU to allow it to go beyond n/a operation. For example...instead of the ECU reading up to a 1600hz signal it can now read up to say 2400hz signal and make fuel and timing adjustments according to that new range. Is that right?
Reply With Quote
  #24  
Old 05-07-2007, 10:37 PM
kcpaz kcpaz is offline
Registered User
 
Join Date: Apr 2007
Location: Gilbert, AZ
Posts: 117
sorry, I don't get your replies until I'm done typing so my replies are a bit behind yours.


Anyway, so basically the JEC engine management is kick-ass compared to the Mitsubishi systems I am describing. It utilizes much more advanced programing to and software to achieve it's tune. It basically simplifies tuning for the common man like myself because I can rely on someone like you to figure out all of the technical stuff for a given range of power and put it together in a package that I don't have to mess with and re-tune every time something changes.

Last edited by kcpaz; 05-07-2007 at 10:40 PM.
Reply With Quote
  #25  
Old 05-07-2007, 10:38 PM
longassname's Avatar
longassname longassname is offline
Just some dude.
 
Join Date: Sep 2002
Location: Miami, FL
Posts: 3,986
Significant Technical Input
It doesn't have anything to do with frequencies but yes Stage 2 expands the operation range of the stock ECU. I uses a mass air meter meter which can measure roughtly twice as much air, fuel injectors which can deliver the fuel to match, and has tables that cover higher load ranges that na operation.



Quote:
Originally Posted by kcpaz
I think I get what you are saying now. What the stage 2 does is it expands the operation range of the stock ECU to allow it to go beyond n/a operation. For example...instead of the ECU reading up to a 1600hz signal it can now read up to say 2400hz signal and make fuel and timing adjustments according to that new range. Is that right?
Reply With Quote
  #26  
Old 05-07-2007, 10:42 PM
longassname's Avatar
longassname longassname is offline
Just some dude.
 
Join Date: Sep 2002
Location: Miami, FL
Posts: 3,986
Significant Technical Input
It is much more "kick-ass" than the mitsubishi system you are describing. The real difference though is that you are describing piggy back stuff where as I am able to and have propperly reprogrammed the SVX ECU so that the common man like yourself doesn't even have to worry about trying to tune. Just plug it in and it will work.



Quote:
Originally Posted by kcpaz
sorry, I don't get your replies until I'm done typing so my replies are a bit behind yours.


Anyway, so basically the JEC engine management is kick-ass compared to the Mitsubishi systems I am describing. It utilizes much more advanced programing to and software to achieve it's tune. It basically simplifies tuning for the common man like myself.
Reply With Quote
  #27  
Old 05-07-2007, 10:48 PM
kcpaz kcpaz is offline
Registered User
 
Join Date: Apr 2007
Location: Gilbert, AZ
Posts: 117
Well hey man, I really appreciate you taking the time to educate me. The reason I became interested in all of this is that I'm putting an SVX engine into an early Porsche 911 and I was doing research on the factory engine management. I'm going to run it N/A at first, but I have plans for a turbo once I know that I can keep everything cool enough. I just scored an ECU that is supposed to have a stage 2 chip in it (2v7 I hope) and it's nice to know that I won't have to spend hours and hours trying to figure out how to tweak and tune the engine management to make it reliable and powerful tune. It's rather focus more of my time doing what I'm good at (fabrication) and less time trying to learn electronics and how the different systems work. I'll leave that to the smart guys like you

I was afraid I might have to go full stand alone but it doesn't sound like I'll have to. And why would I?

Last edited by kcpaz; 05-07-2007 at 10:50 PM.
Reply With Quote
  #28  
Old 05-07-2007, 10:50 PM
longassname's Avatar
longassname longassname is offline
Just some dude.
 
Join Date: Sep 2002
Location: Miami, FL
Posts: 3,986
Significant Technical Input
Look for obi in the piston thread. He has a porsche with an eg33 in it.
Reply With Quote
  #29  
Old 05-07-2007, 10:54 PM
kcpaz kcpaz is offline
Registered User
 
Join Date: Apr 2007
Location: Gilbert, AZ
Posts: 117
REALLY!!!??? you got a link? I would love to see some pictures.
Reply With Quote
  #30  
Old 05-08-2007, 06:27 PM
immortal_suby's Avatar
immortal_suby immortal_suby is offline
Thread Killah
Alcyone Gold Contributor
 
Join Date: Feb 2001
Location: Greenville, SC
Posts: 5,835
Registered SVX
Quote:
Originally Posted by kcpaz
Well hey man, I really appreciate you taking the time to educate me.
Me too! This was a good discussion, I understand much more about the system now.

Got a quick question

I have finally secured (8) used 370cc injectors now but from 2 different engines. All are the sr20DET purple tops.
Without running NO2, am I safe to just pick the best looking 6 and drop them in along with 2v7 and see how she runs, or should I wait and send them off for matching/blueprinting. I have thursday off and an itchy set of tools that want to see how 2v7 runs......Please, I need a good reason not to drop them in if there is one. I am an excitedly impatient bastard sometimes.
__________________
Matt
Locker Link
2015 BRZ Limited 6MT
92 Ebony LS-L ECUtune Stage2av1, Z32 MAF, 370cc injectors, TomsSVX intake, BontragerWorks 22mm RSB #003, HID Hi and Lo beams, OT endlink and bushing mods, PWR Aluminum radiator, Harvey's QC shift kit, 2.5" flowmaster 80 exhaust, 17" Michelin Pilot Sport A/S, Poly sway bar bushings, Slotted Bradi rotors, AFBeefcake powdercoated calipers, 97 grill, and a huge set of air horns. 300,000 miles and counting
92 Ebony LS-L. ecutune stage1v4, motorsport 1pc pulley. Garage Queen - sold to Dad in upstate NY 155,000 miles
19 Subaru Ascent Premium - -Hers !.
89 DL 4x4 little red wagon - a.k.a. The immortal suby. 275k R.I.P.
Reply With Quote
Reply

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -6. The time now is 05:42 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
© 2001-2015 SVX World Network
(208)-906-1122